Maximum torque from a Commando.

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acotrel

acotrel

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I am interested in putting my 850 on a dyno to see what the torque figure is. Often on this forum horsepower figures have been quoted, but they mean nothing to me. What is more important is the maximum torque figure and the revs at which it occurs. I'd be interested to know what other tuners have achieved, or perhaps torque measurement on most dynos is too unreliable to be of real use ? Most Commandos won't cop over 7000 RPM regularly without destroying themselves , so the torque factor is the most important. An improvement in torque allows higher gearing to be used with comfort, so the bike is faster. If the torque graph is erratic on the dyno, comparisons of torque before and after modifications, will be more difficult.
 
My race motor is over 60ft lbs of torque and makes 42 ft lbs at 3500 rpm, 52 ft lbs at 4000 rpm 60 ft lbs at 5252 rpm and 60 bhp at that same point and finally 53 ft lbs at 7000 rpm and 71 bhp also at 7000 rpm .
It holds its torque all the way through the rev range which makes it a very tractable motor and a pleasure to use knowing you can make good power/torque everywhere.
Regards Mike
 
Thanks very much for that, it is the sort of information I am seeking. Does your motor have a 2 into 1 exhaust system and a race cam ?
 
Every dyno is different so the bike to bike numbers have little meaning, unless all are done on the same dyno.

For example ,one of the contributors to the Triumph site is a dyno operator. He just installed a new Windows program in his setup. He tested some bikes which he had dynoed immediately before installing the new program. All power figures are up by 10 %.
Which is correct, the old number or the new number? People like the bigger number so I'm sure he'll stay with that as correct.
The only dyno numbers of use are before and after on same dyno with same operator, ( as Nigel & Fullauto have done) but even those seem to vary quite a bit with no change to the bike.

I use a hill, it's always the same !

Glen
 
I think some folks look at the hp and tor. curve / lines that are established on the rolling roads and the big numbers are maybe secondary .... it may be interesting to look at the before and after sheets ( of same bike on new program ) and compare the curve as opposed to just the ultimate numbers ....
Craig
 
The power figures are calculated by the software on the respective dynos's as it is the torque that the dyno's measures.
Putting the correct data and engine specs into the software can have an effect on final figures as well, so be careful when entering this base data.
The O2 sensors are mostly designed for unleaded fuels, so can get saturated using leaded avgas, so a saturated sensor can give poorer readings the longer the testing takes.
My race motor has been tested on three different dynos using three different operators over the last 5 years of development.
It has the same head with no changes, the same carbs and manifolds, the only changes being main jet sizes.
It runs the same ignition system (the only timing change is from 28 deg to 32 deg now settled on 29 .5 deg)and the same fuel (avgas)
The cam is also the same, the only two major changes have been the exhaust system and new rings .
My results are within 5 bhp at the back wheel with all three dynos, so I take the lowest value as the correct one.
The highest being 76 the lowest 71 bhp
The cam is a JS2 and the current exhaust is a 2EX1 R that we make here in NZ and loosely based on Steve Maneys units.
Most dynos come with a barometric sensor built in which has input to the end calculation, a big change in outputs can be recorded if the dyno doesnt have one.
Glen , I bet the exact same daytime elements are different everytime you attack that hill?
Regards Mike
 
I think a dyno is a great device for tuning. If I had cheap access to one I would use it.
The cost here is $160 minimum per outing, more if you take up more than an hour of time.
The hill is free and works remarkably well.
The temp/ humidity doesn't seem to change speed at top enough to count. Unless the bike is out of tune I see the same speed at top +- 1 mph every time .
If the tuning is out then a drop of 2-5 mph or more will show, depending on how far out things are. Tuning always ( so far) gets the speed back.
I keep log books for all the bikes and have recorded the top of hill speeds for each.

With the EI bikes there is very little tuning. With points type ignition things do get out a bit every ten thousand kms or so.
The hill let me know that it was time to replace worn out carbs on one bike. It still ran fine, but lost 3 mph on the hill. I tried all of the usual stuff, but the speed wouldnt come back. Fitted new Premieres and it was right back to the old speed.

Glen
 
I like the sound of your hill Glen!

Dyno time is very cheap for me, if the guys aren't busy, I can occupy it for half a day or more and we just agree a 'reasonable' figure.

Its a bit of a drive, and requires me hiring a van usually to take parts and tools and etc. so my biggest obstacle is normally finding the time and that time matching up with the dyno shop calendar.

Still wish I had similar hill to yours here though !
 
If you NEED a dyno, you're spending more money than I'll ever have!

hee hee

I know the perfect hill for me, I never considered the use of it in that manner...
 
I was racing in the South Island of New Zealand a few weeks ago at the Mike Pero Southern Classic, I found my bike was running very rich due to the exceptionally hot days, as did a few of my fellow racers, so weather conditions can make a big change in settings.
I had a low side crash in the 3rd race of the first days racing, but thats another story.
Im in the process of completing a dyno set up that came with my 650 SS race bike, all the hardware in the way of a framed bench , roller , starter and braking system is all there.
I will be purchasing a Performance Trend Datamite and other hardware to complete the project.
Another racer friend and I are going halves in the project and we are incorporating all in a trailer for portability.
Regards Mike
 
Brooking 850 said:
Im in the process of completing a dyno set up that came with my 650 SS race bike, all the hardware in the way of a framed bench , roller , starter and braking system is all there.
I will be purchasing a Performance Trend Datamite and other hardware to complete the project.
Another racer friend and I are going halves in the project and we are incorporating all in a trailer for portability.
Regards Mike
Click to expand...

Just calibrate it between 71-76 with your race bike, and you'll be golden! Ill be a guinea pig for you.
 
Brooking 850 said:
I was racing in the South Island of New Zealand a few weeks ago at the Mike Pero Southern Classic, I found my bike was running very rich due to the exceptionally hot days, as did a few of my fellow racers, so weather conditions can make a big change in settings.
I had a low side crash in the 3rd race of the first days racing, but thats another story.
Im in the process of completing a dyno set up that came with my 650 SS race bike, all the hardware in the way of a framed bench , roller , starter and braking system is all there.
I will be purchasing a Performance Trend Datamite and other hardware to complete the project.
Another racer friend and I are going halves in the project and we are incorporating all in a trailer for portability.
Regards Mike
Click to expand...

Your own personal Mobile dyno unit? Seriously? And my Missus thinks I get carried away !?!
 
It was an opportunity not to be missed, it was stored in the shed of the guy who built the 650 SS I now own.
I cut a deal with his widow, then got a racing mate involved, bought an old trailer that had a current registration and warrant of fitness, we are now modifying that to suit the dyno frame and will cover it all in.
Then we will purchase the Performance Trend gear and set it up to suit our needs.
That way we can take the dyno to the bikes instead of taking the bikes that are spread all over the country to the dyno facilities.
Lots to learn though.
Brian G CR is 10.5 :1 JSM light weight pistons
 
What does a dyno torque figure mean when there is no primary standard for calibration ?
 
Mike, i cant wait to see this set up.
I hope there will some words and a few pics for the newsletter.
iain.
 
Hi Iain , yes there will be.
Current progress on the dyno, trailer completed, dyno frame modified to suit trailer.
All dyno hardware now purchased from Performance Trends and hand carried into NZ from the States.
That creates a saving!!!
Software downloaded using Windows 10.
Cladding for boxing out the trailer has been ordered and should be supplied next week.
Its happening
Regards Mike
 
I paid $40 for two pulls at the Cabbage Patch near Daytona. Cheap as chips.
 
I found a local speed shop with a dyno; they only "allow" Harleys to run. ??? Maybe they're afraid of being embarrassed by a lil ol' 850 antique.

Nathan
 
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